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By S. F. Böde, K. Böde

This paper focuses on developing a comprehensive and pragmatic information technology (IT) strategy for low-margin construction activities. This forms part of the realignment of the general business strategy, and refocusing the operational model. The main elements of the IT strategy formation are analysis of the current IT environment in terms of software and hardware, carrying out a gap analysis, and developing individual functional digitalisation strategies in construction execution based on Building Information Modelling (BIM), business administration processes, communication, business intelligence (BI) and reporting, and data security. Further, substantial emphasis is given to the sustainable strategy implementation in terms of hardware and software readjustments, their integration, user training, and defining the way forward.

Sep 1, 2021

If an orebody has been drilled to achieve some level of regulatory compliance, then a number of associated geological databases will exist, representing 10 000 to 100 000 m plus of core intervals. The databases usually contain data about assays, lithology, mineralisation and geophysical attributes. They will also include location information such as collar positions and downhole surveys. Obviously this data is collected by geologists for, predominantly, geologists and mining engineers. However, from a process design viewpoint process engineers usually ignore the geology where possible and rely on a small number of metallurgical test samples. Typically these test samples are sourced from convenient and available cores or from a small number of specially drilled metallurgical holes. One of the worst instances known to the author was the design of a SAG mill using only two SAG specific test results (one for each of the major ore types) while, geologically, the orebody was defined by more than 30 000 m of drilling. This paper sets out a philosophy to maximise the use of the geological data, both for process design and in preparation for the commissioning phase of projects. Geological data is used in the identification of preferred locations for metallurgical test samples, for checking the metallurgical validity of the geological ore-type definitions, where necessary developing new ore-type definitions (geometallurgical domains) and developing mathematical relationships for the estimation of important metallurgical factors across the geological database. If the estimation of factors (for example ore competence) is considered reliable enough then there is also the possibility of feeding calculated data back into the block modelling process to allow the generation of metallurgically relevant outputs in the mine plans.

Jan 1, 2007

By F. S. Hoseinian, D. Deglon, L. leal Filho, M. Safari, T. C. Souza Pinto

This paper investigates the effect of chemical and physical operational parameters on the reverse flotation of Timbopeba itabirite iron ore in a pilot-scale pneumatic flotation cell. Operational parameters include collector and depressant dosages, feed rate, superficial gas velocity and solids concentration. Results show that increasing collector dosage results in an increase in quartz recovery, particularly for the coarser quartz where recovery increases by nearly 30%. Increasing depressant dosage results in a decrease in both quartz recovery and hematite loss, for the coarser hematite particles. Increasing the feed rate has no effect on quartz recovery or hematite loss, suggesting that the pneumatic flotation cell is not residence time constrained. Increasing the superficial gas velocity results in an increase in quartz recovery to an optimum at a Jg of around 0.6 cm/s after which it decreases significantly, particularly for the coarser particles where recovery decreases by as much as 50%. Decreasing the solids concentration does not affect quartz recovery but results in significant decreases in hematite loss. Here, fine and coarse hematite loss decreases from around 25% to 12% and 10% to 2% respectively. Superficial gas velocity and solids concentration are operating parameters which have the largest effect on the flotation performance of the pneumatic flotation cell. Results suggest that this flotation cell should be operated at relatively low superficial gas velocities and solids concentrations. However, these are pilot-scale findings and would need to be tested at an industrial-scale where different operating conditions may be optimal. Keywords: Operational parameters, reverse froth flotation; entrainment; iron ore

Jan 1, 2020

By R. C. Urquhart, W. P. Channon, D. D. Howat

Discussion: The mode of current transfer between electrode and slag in the submBerged-arc furnace by w. P. CHANNON, R. C. URQUHART, and D. D. HOWAT J. MEINTJES I have read the paper with much interest, and I should like to make a few observations. (I) The experimental work deals with resistance heating by an electrode immersed in a slag... AUTHORS' REPLY We thank Mr Meintjes for his critical analysis and helpful comments arising out of his study of our paper. Possibly we should emphasize at the outset that our experiments all related to the conditions in which the lower portion of the electrode was immersed in molten slag. We believe, however,

Jan 12, 1974

By S. L. Crouch

A. C. Dieringt The procedure described by Professor Crouch for the modelling of mining in faulted ground allows the elastic and inelastic deformation to occur simultaneously, that is, fault slip occurs while an element is being mined. The energy release rates (ERR) shown in Crouch's Fig. 10 are apparently calculated from his equation 9 using the i total deformation Din (see the upper load line of Fig. I) Refractories The institute of 'Gesteinsh iittenkunde' of the technical university at Aachen, the Refractories Research Institute at Bonn, and the Verein Deutscher Eisenshiittenleute (VDEh) at Diisseldorf are to hold the XXII International Refractory Colloquium on 27th and 28th September, 1979, at Aachen.

Jan 1, 1979

By F. L. D. Cloete

The following discussion relates to the paper by G. S. Hansford, C. D. Levy, and J. W. de Kock that appeared in the March 1976 issue of the Journal (vol. 76, no. 8, pp. 363-369) Competition for student members Each year the South African Institute of Mining and Metallurgy offers a prize (or prizes should the entries warrant it) of up to RI00 for the best paper or dissertation on a topic appropriate to the interests of the Institute. Engineering in South West Africa The SW A Engineering Profession Steering Committee was established on 4th April, 1977, its purpose being to formulate an Act covering the engineering profession in South West Africa.

Jan 1, 1978

For the Gold Fields Foundation National Engineering Awards, each university affiliated to the South African Federation of University Engineering Students (S.A.F.U.E.S.) selected a candidate who, in their opinion, presented the most outstanding design project in their final year during 1984. New President On 29th March, 1985, Mr B.C. (Bertie) Oberholzer, Manager of East Driefontein Gold Mine, was elected President of the Association of Mine Managers of South Africa for the ensuing year. Bullion from old film A pollution-free chemical method of producing silver that is 99 per cent pure-and therefore of bullion quality-from scrap photographic film and paper has been developed by a British company.

Jan 1, 1985

By J. P. G. Pretorius, T. C. Partridge

The analysis of angular atypicality of lineaments as an aid to mineral exploration by J. P. G. PRETORI USc, M.Sc. (Pret.) (Visitor) and T. C. PARTRIDGE, Ph.D. (Natal) (Visitor) In an exploration project, data pertaining to 84000 lineaments in an area of 25 000 km2 were recorded. The total length of lineaments in intervals of one degree was determined. Angular intervals with Iow length densities were regarded as atypical. The proportion (by length) of lineaments with such atypical orientation was calculated for 5 km X 5 km grid squares. This index of angular atypicality was contoured and, used in conjunction with conventional photogeological techniques, contributed in a large measure to the success of the investigation.

Jan 5, 1974

By M. J. Southwood

SYNOPSIS Experiments carried out under atmospheric pressure and temperature (25°C) and sterile conditions show that the dissolution rate of nickel and copper from a pyrrhotite-pentlandite-chalcopyrite ore in a lixiviant of sulphuric acid is greatly enhanced in the presence of pyrite. At a pH value of 1,8 and in the presence of pyrite of equal mass to that of the ore, the recoveries of nickel and copper improved dramatically (21 and 80 per cent respectively). At a pH value of 4,0 the recovery of nickel was enhanced, but the chalcopyrite was refractory. A galvanic mechanism is probable, but cannot be proved from these experiments. The economic implications of the results are discussed.

Jan 1, 1985

By F. P. A. Robinson, C. R. Thomas

Stress-corrosion studies on materials used for surgical implants * by C. R. THOMAS and F. P. A. ROBINSON Samples of Vitallium (a cobalt-chromium alloy), 316L stainless steel, and titanium T318 were subjected to the boiling magnesium chloride test so thattheir susceptibility to stress-corrosion cracking could be determined, and their behaviour under service conditions was then assessed. Stress-corrosion cracking was confined to the stainless-steel samples, while gross pitting was detected in the samples of forged Vitallium. It was concluded that the use of stainless steel should be avoided for long-term surgical implants. Surface imperfections on the stainless steel are generally the cause of pitting, from which stress-corrosion cracks are sometimes propagated.

Jan 11, 1976

By E. G. Galvez, E. Mate, L. A. Cisternas, C. Cruz, L. Cortés, M. E. Osorio

Designing and optimising flotation circuits are critical for mineral beneficiation plants, and therefore several procedures have been published. The modelling of flotation circuits with the objective of design and optimisation is problematic in that different approaches are used for the modelling of flotation units and regrinding units. Usually, regrinding models are based on particles characterised by their size, while flotation models are based on species characterised by fast and slow classes. The relationship between particle size and liberation can be used, but it requires laboratory studies that are time-consuming and costs are high. It is therefore not surprising that few studies on flotation circuit design and optimisation include flotation units and regrinding units simultaneously. In this paper, it is proposed to model the regrinding stage using species characterised by fine-slow, medium-fast, and coarse-slow flotation species. In deep, the regrinding model is derived from a population balance approach based on flotation species. The fraction of these species at the feed and product of the grinding unit is determined by flotation tests. Then, based on these data, the model parameters can be determined by a regression estimation procedure. A local ore was used to validate the model. Keywords: Modelling, flotation circuit, grinding circuit, process design

Jan 1, 2020

By T. van Heerden

A range of supported gold catalysts was prepared by ion exchange, varying many of the preparation variables, including concentration in the precursor solution, washing procedure, as well as drying and calcination procedures. These catalysts have been characterized extensively. TEM images show essentially the same crystallite size distributions, between 2?5 nm, for almost all catalysts, the only exception being catalysts not washed in ammonia, which did not show any small crystallites. Additional characterization with SEM yielded an interesting discovery. Catalysts that appear identical on the TEM also contain some large crystallites in the range of 50?500 nm. Differences in dispersion due to the drying procedure not seen on the TEM can now be observed. Oxygen chemisorption is being investigated as an additional method to characterize gold based catalysts to complement the typically used electron microscope techniques.

Jan 1, 2012

By Q. Zhang, X. C. Wang, S. Mao

Phosphate ore is an important strategic mineral resource in which apatite is the main valuable mineral. Flotation is the most commonly used method to separate apatite from middle-low grade phosphate rock. Selective flotation separation is based on the difference of physical and chemical properties of minerals occurring at the three interfaces of mineral/bubble/water. Surface and interface chemistry of mineral have been playing an important role in interpreting and governing its flotation phenomenon. In-situ, visualized and high-precision analytical techniques, such as Time-of-Flight Secondary Ion Mass Spectrometry, Atomic Force Microscopy and Molecular Simulation, have been applied to explore and uncover microscopic nature of apatite flotation. Consequently, a great progress at molecular or atomic level on surface and interface chemistry of apatite flotation has achieved in the past decades. In this paper, the research progress of surface and interface chemistry of apatite flotation such as surface wettability, surface-charging characteristics, surface dissolution behavior, adsorption mechanisms of fatty acid collector and depressor on apatite surface were systematically reviewed. This review will be helpful for the development of more selective reagents and efficient technologies for apatite flotation. Keywords: Apatite, Flotation, Surface and interface chemistry, Surface analysis technology

Jan 1, 2020

By K. Shame, H. H. Thiele

South Africa holds approximately 70% of the world’s total chrome reserves. Chromium is an important raw material for the production of stainless steel and ferrochrome alloys. Over the years, China’s ferrochrome market has been dependent on chrome ore imports from South Africa. In 2018, China imported about 75% of its chrome ore from South Africa. With the low platinum price and the rising demand for stainless steel, a growing demand to evaluate new beneficiation technologies for fine chromite was identified. Gravity separation of fine chromite (<75 μm) is inefficient, due to the limitations of the technology to upgrade fine particle size distributions. Potential for the recovery of chromite, specifically fines (<75μm), lost to UG2 PGM flotation tails, but also from MG and LG6 spiral circuit tailings exist. Flotation of podiform chromite ores from India and Kazhkhstan is successful in generating saleable product grade, following acid or alkaline flotation routes. Application to South African stratiform chromite is being evaluated, with the emphasis on evaluating reagent type, optimising dosages and the effect of pH in optimising flotation performance. Flotation can unlock additional value from chromite tailings material. The effect of ore characteristics such as gangue mineralogy, particle size distribution and headgrade are reported. The performance in terms of product quality and yield are evaluated and compared. The impact of this paper will not only prolong life of mine and increase revenue but will also alleviate environmental burdens associated with tailings dams. Keywords: Chromite, flotation, fine material, performance optimisation

Jan 1, 2020

By G-L. Wu, X-B. Liu, C-Y. Zhou

"The static recrystallization behaviour of Ti-Nb microalloyed high-strength steel during hot deformation was studied by conducting double-hit hot compression experiments using a Gleeble-3500 thermomechanical simulator. The effects of deformation temperature, strain rate, strain, and initial austenite grain size on the static recrystallization fraction are discussed. The static recrystallization kinetics were modelled, and the results show that the static recrystallization fraction increased with deformation temperature, strain rate, and strain and interpass time. The static recrystallization activation energy Qs was 326.05 kJ mol-1. Comparison of the experimental results and predicted results indicates that the effects of deformation parameters on the static recrystallization in multistage hot deformation are significant. The predicted results are in good agreement with the experimental results. IntroductionIn hot-forming processes, complex microstructures are often induced by multiple hot deformation mechanisms (Zhang et al., 2014; Liang et al., 2015). The softening behaviour during hot processing has generated considerable interest because component properties are influenced significantly by the corresponding microstructural evolution (Wu et al., 2010). It is well known that dynamic recrystallization (DRX); metadynamic recrystallization (MDRX), which occurs by the growth of DRX nuclei during intervals of deformation; and static recrystallization (SRX), which occurs by nucleation and growth during the intervals of deformation, can significantly alter the austenite grain size (Chen et al., 2015. Chen, Sui, and Cui, 2014; Mao et al., 2014). The long interpass times allow complete SRX to take place if the steel is being rolled above the interpass recrystallization stop temperature (Tnr), i.e. in the absence of carbonitride precipitation (Siciliano, 2000). In recent research, microalloying technology coupled with new-generation thermomechanical control processing (NG-TMCP) has proved efficient in achieving the proper balance between strength, toughness, ductility, and formability by means of a suitable combination of chemical composition and thermomechanical treatment parameters (Shukla et al., 2012; Bandyopadhyay et al., 2011). The alloying elements Nb, V, Ti are widely used in high-strength low-alloy (HSLA) steel to achieve the desired strength and toughness properties with solid-solution strengthening, precipitation hardening, grain refinement, and dislocation strengthening (Opiela, 2014; Chen and Yu, 2012). The wide applicability of alloying elements in HSLA steel is due to the fact that heat treatments are not required after forming of the parts, which results in time and cost savings."

Jan 1, 2017

By A. Fouchee, N. Naudé, K. Schommarz

"This article presents laboratory test work conducted on an African haematite ore to determine the influence of the flotation pulp pH on the final iron grade and recovery. Results show that a combination of an isodecyl ether propylene amine/amino acetate and 1,3-propanediamine, N-(3-(C10-C16-alkyloxy)propyl)-derivatives collector is suitable for separating haematite from quartz. Higher iron grades were obtained at pH levels between neutral and pH 9. This underlines the importance of the surface charge effect of the ore on its flotation characteristics. The results serve as good baseline conditions for further optimization. IntroductionBeneficiation of iron ore by flotation is widely used in Brazil, India and China. In Africa, however, this practice is not yet commercially developed.The aim of this test work is to serve as a starting point by establishing suitable pH conditions for the development of a practically implementable reagent suite, which will then be included in a larger beneficiation circuit for producing high-grade iron ore sinter feed.In the literature, African iron ore types are graded as low-grade (60.0–62.9% Fe; 8.6– 12.5% SiO2 and insolubles), high-grade (66.0– 69.9% Fe; 0.8–4.5% SiO2 and insolubles), and meduim-grade as the remaining portion (Astrup et al., 1998). The low-grade ore used in this work contains less than 60% Fe.For Brazilian ores consisting of a combination of haematite and quartz, it is common to use corn starch as a depressant and ether amine blends as collectors with additional frothing characteristic (Araujo et al., 2005). Work by Turrer and Peres (2010) shows the possibility of using other depressants successfully as well.The main mechanism of the reverse flotation of quartz from iron ore is based on the electrostatic theory of flotation. This is due to the strong pH dependence of the zeta potential of the mineral edge planes on silicate particles (Fuerstenau and Pradip. 2005)."

Jan 1, 2016

By S. A. Hosseini, O. Asghari

"Recoverable mineral resources assessment has become a standard geostatistical application in the mining industry, with various geostatistical techniques currently available. This investigation aimed to improve the prediction at the Sungun deposit and to obtain mineral resource models capable of handling (i) the change of support from drill-hole composites to selective mining units (SMUs), (ii) the multivariate nature of the ore control selection criteria that involves both copper and molybdenum grades; and (iii) the local uncertainty on the true (unknown) grades. The solution presented in this paper is to use direct block-support sequential cosimulation in order to construct a set of alternative outcomes of the copper and molybdenum grades on block support over the deposit, with no need for storing point-support values, hence with a considerable gain in memory management and CPU time. The grade realizations so obtained are then processed to calculate the uncertainty in the mineral resources that can be recovered above given cut-off grades, both globally and on a blockby- block basis. IntroductionGeostatistical methods are widely used by mining companies to determine a resource model of the tonnage and head grade of a potential orebody, which is one of the first and most critical inputs underpinning any mining project. The prediction of the grade, tonnage, and recoverable metal for a particular mining plan and the corresponding financial forecast constitute the main technical risks in mineral resource evaluation. The conventional approach to this problem is to predict the mineral grade for constant volumes relevant to the mining plan and to base the recoverable mineral resource calculations on those predictions. Alternatively, one can directly predict the local variability in the mining block grades based on a spatial distribution model (David 1988; Rossi and Deutsch 2014). Multiple realizations can also be constructed by conditional simulation, providing a more complete representation of block grade uncertainty, as well as the uncertainty over multiple blocks. Simulation methods allow quantification of the uncertainty of the mineral resource prediction risks in downstream studies such as mine design, mine planning, or operational optimization studies; the risk assessment is achieved after applying transfer functions to the conditional simulation models (Dimitrakopoulos 2012; Rossi and Deutsch 2014)."

Jan 1, 2017

By L. S. Linda, P. G. H Pistorius

Ferritic stainless steel is utilized to fabricate automotive exhaust systems using a ferritic weld metal. Ductility of the weld metal is higher if its microstructure contains a significant proportion of equiaxed grains. The formation of equiaxed (rather than columnar) grains is favoured by a higher titanium weld metal content. In this study, the Ti content of ferritic stainless steel weld metal was changed by using Tifree (Type 436) and Ti-containing (441) ferritic stainless steel as base metals. The metal-cored welding consumable contained 0.4% Ti. Gas–tungsten arc welding and gas–metal arc welding processes were compared. The weld metal Ti content ranged from zero to 0.5% Ti, as determined from scanning electron microscopy supplemented by inductively coupled plasma optical emission spectroscopy. Cross-sections of the weld beads were subjected to point counting (to estimate the fraction of equiaxed grains) and image analysis (to estimate the average grain size). Point counting proved to be more reliable. The fraction of equiaxed grains was sensitive to the Ti content, but not to the welding process. Below 0.4% Ti, the fraction of equiaxed grains gradually increased with an increase in the weld metal Ti content; above 0.4% Ti, the fraction of equiaxed grains rapidly increased with increasing Ti content. The transition in behaviour at 0.4% Ti corresponded to a Ti content at which Ti-rich precipitates became stable at the estimated liquidus temperature of the weld metal.

Jul 2, 2022

By K. Sasaki, Y. Oriia, Shigeto Kuroiwa, H. Miki, Yuji Aoki, T. Hirajima, G. P. W. Suyantara

The effect of a sulfite reagent on the floatability of chalcopyrite and enargite was investigated in this paper. The flotation tests using single and mixed minerals were performed under various concentrations of sulfite. The flotation tests using a single mineral showed that the sulfite reagent depressed the natural floatability of both minerals at pH 9. Surprisingly, enargite was floated after the addition of potassium amyl xanthate (PAX) following the sulfite treatment, and the floatability of chalcopyrite depressed under a similar condition. X-ray photoelectron spectroscopy analysis results showed that the sulfate species increased after the sulfite treatment on both minerals. However, the addition of PAX removed this sulfate species and rendered the enargite surface hydrophobic. This phenomenon was not observed on the chalcopyrite surface. FTIR analysis and PAX adsorption studies were performed to support this finding. The flotation of a mixed mineral was in agreement with the flotation of a single mineral, indicating a possibility for selective flotation of chalcopyrite and enargite using the proposed method. Keywords: Flotation, chalcopyrite, enargite, sulfite, potassium amyl xanthate

Jan 1, 2020

By M. Rudolph, R. Tolosana-Delgado, G. van den Boogaart, M. Reuter, U. Peuker

This paper addresses the challenge to define a concept of entropy (state of order) for a textured particle system. Both the particle texture, the intergrowth respectively, and the particle size influence the order of a particle system. The smaller the particles become, the more particles form the solid system and the more permutations of the structure of the particle bed are possible. The texture within a particle is fixed, as long as it is not subjected to changes due to comminution, flocculation or agglomeration. The paper will present a definition of entropy, which is able to reflect qualitatively and quantitatively the intergrowth and the size (distribution) of the particles. Theoretical examples will show how different breakage mechanisms can be identified using the entropy definition. Furthermore, we will define the specifications for data sets to calculate the entropy of a particle system. Keywords: Milling, mineral liberation, intergrowth, statistical entropy, modelling

Jan 1, 2020